The sensory world of animals and humans alike is enormously complex. Our current understanding of how multisensory inputs are processed in the brain for perception and behavior remains rudimentary at best in any animals. The genetically tractable Drosophila larva offers a unique opportunity for behavioral and neurobiological studies of the integration of multiple sensory modalities for perception and behavior. Fly larvae display a rich repertoire of complex behaviors, and have a highly evolved yet numerically simple central nervous system (CNS). The brain of fly larvae shares many similarities with the human brain including two hemispheres with high local clustering of neurons (also named the local processing unit or LPU) and long-range projections, six major neurotransmitters, a variety of neuropeptides. An increasingly large set of powerful molecular genetic and neurobiological tools available will further allow us to perform in- depth follow-up studies of the neural substrates and processes underlying a neural process or behavior of interest. We have recently shown that like in mammals, attractive food odors elicited reward-driven overeating of readily accessible sugar-rich food in Drosophila larvae. Deficiencies in the dopamine (DA) system blocked the capacity of the appetitive odor to elicit the appetitive behavior. We have also identified a small number of third-order olfactory neurons that synthesize DA. Activation of these DA neurons mimicked the behavioral effect of appetitive odor stimulation. On the other hand, the OA system mediates larval feeding response to readily available sugar media. This application will be focused on exploring multisensory integration for food perception and behavior in the fly larva model by testing several key aspects of a novel working model. The proposal has two specific aims: 1) behavioral and neurobiological studies of integration of multiple olfactory and gustatory modalities in modulating appetite for palatable food; 2) analyses of the effects of brain states on integration of olfactory and gustatory modalities in modulating appetite for palatable food. We expect that the successful outcomes of these studies will provide novel insights into integration of different olfactory and gustatory modalities in modulating appetite for palatable food. Furthermore, the knowledge gained from these studies will contribute to the general understanding of the integration of multisensory modalities for perception and behavior as well as related neurological disorders.